i thought you sold it ages ago. rare as hens teeth. once in a life time oportunity for someone. i only really know of about 2 of these 400 Z's elsewhere and they were in canada and being dismanltled and sold in pieces so no longer exist as complete bikes. i bought the forks off one from canada as they are an improvement over the X models. we have about 90 members in the PE forum world wide yet no one else owns or has seen a 250 or 400 Z. i have seen about 2 250 Z's advertised ( no photos though) at wreckers in just bikes but you dont really know if they are just a 81 model. last year i did see a 250 z at a bike swap meet. it didnt sell as it was very, very rough. its down at 2 wheel recyclers at Hackam south of Adelaide if they havent sold it yet.
http://www.twowheelrecyclers.websyte.com.au/from the 2 photos i have seen of Firkos 400 Z, it is very original low use bike but is missing the unique Australian market Z model tail light and the blinkers and mirror etc and has the usual white faded headlight.
also look for folding tip gear and brake pedals, different sprocket cover (same as later RM's i think), different side stand, a reflex reflector on rear fender, extra reinforcement under rear fender, extra rubber mount over rear frame loop for fender, and im 99% certain they should have dodleg brake and clutch levers and 2 piece rubber covers with quick adjusters like the 82-84 175 Z. my Z top triple clamp is differnent to my T models but its only the shape of the casting. forks are different. the sliders are machined different inside, the chrome legs are differnent and have guide bushes fitted. im pretty sure parts of these are same as mid 80's enduro model DR250 forks. not sure aboit damper rods and valving though. and different decals.
there probably a few more things aswell but ive forgot. i have Z microfiche parts cards but havent found any one who can print, scan or view them yet. when i can view this info i may discover more differences.